An Indian court has denied bail to a doctor jailed for life for allegedly helping Maoist rebels. Human-rights activists and academics both inside and outside the country have been calling for his freedom.

A High court in Bilaspur in Chhattisgarh State turned down the bail petition of 60-year-old Binayak Sen, a doctor who has worked for decades among the state’s poor and tribal communities.

Sen was sentenced in December to life in prison for sedition and conspiracy after being found guilty of passing notes from a jailed Maoist leader he was treating and helping the rebels open bank accounts. He has appealed his conviction.

The sentence was slammed by civil-rights campaigners who say he is being victimized for highlighting human-rights abuses.

There have been many appeals made to the Indian government for his release, the latest by 40 Nobel laureates, who called him an "exceptional, courageous and selfless colleague."

The South Asia director of Human Rights Watch in India, Meenakshi Ganguly, said human-rights campaigners are disappointed at the rejection of bail for the doctor. She called it a setback for human-rights activists in the country.

"Binayak Sen enjoys international attention and support ... when something like this happens, then it seems as if the authorities are trying to silence critics,” Ganguly said. “In that case, people who are working on the grass root level, who do not have the kind of profile Binayak Sen enjoys are going to be much more fearful, and that is really hurtful for Indian democracy."

Amnesty International has said that Sen’s trial violated international standards, and the charges against him are politically motivated.

The case has also raised concerns that India’s anti-terror laws are too sweeping.

Sen, a trained pediatrician, has won international praise for his work in Chattisgarh. The medical clinics he ran for some of the poorest people in the state helped bring down infant mortality rates. He has denied supporting Maoist rebels.

Chhattisgarh is one of India’s poorest states, and one of the worst affected by a violent uprising by Maoist rebels.